In the prior art, optical sensing method has been widely applied as one of the methods for detecting whether an ink cartridge for an ink jet printer has been mounted in place.
In common detecting technique, an ink cartridge must include two detecting mechanisms, a first detecting mechanism and a second detecting mechanism, so as to ensure the ink cartridge can be recognized by an ink jet printer after being mounted to the ink jet printer. Such a detecting technique is achieved primarily through shielding, by the detecting mechanisms, the signal path of a sensor in the ink jet printer. For example, Chinese patent No. CN201020186335.4 discloses an ink cartridge for an ink jet printer, where the detecting mechanisms thereof are a first signal shielding part 2 and a movable lever member 6, the detection principle is that: during mounting of the ink cartridge, the movable lever member 6 firstly shields a signal from a second sensor of the ink jet printer; subsequently, the first signal shielding part 2 shields a signal from a first sensor of the ink jet printer; subsequently, as the ink cartridge continues to be mounted, the movable lever member 6 rotates in an direction opposite to the mounting direction, under a combined action of a resetting member 4 and a tension generating member 5, and deviates from a signal path of the second sensor, and thereby does not shield the signal from the second sensor any more. As such, the printer can judge that the ink cartridge has been mounted normally. However, there are many potential problems in the above technique for mounting and detecting the ink cartridge, for example, since the movable lever member is supported by an elastic sheet, and after the ink cartridge are mounted repeatedly for many times, the movable lever member cannot return to the initial position due to deformation of the elastic sheet, which affects mounting and detecting of the ink cartridge in the next mounting and causes the ink cartridge to be unusable. Moreover, the movable lever member is susceptible to external influence, and thereby rotation thereof is affected, thereby causing failures of mounting and detecting and the use of the ink cartridge.